The Biostatistics Core provides biostatistical, computing and data management services to all the CPRU investigators. The core provides statistical expertise in all stages of the projects, including initial design and sample size calculations, interim reporting and data analysis, and final analyses for the preparation of manuscripts based on the projects. Some projects require specialized statistical expertise; support for these analyses will be provided by statisticians assigned to those particular projects. The biostatistics core will be primarily responsible for integrating the statistical activities of all projects within the CPRU. The core is also responsible for developing, maintaining and coordinating the central database for the CPRU projects. It provides the programming expertise to create data forms, data entry screens and to integrate data from the different projects. The core also provides the essential services of merging, retrieving and transferring data from the central database, for use in creating the tailored intervention and telephone counseling materials.